In the shaping of synthetic resins such as polyolefin resins, polyurethane resins, epoxy resins and polyamide resins, additives such as waxes are used to enhance releasability of shaped articles from a mold or to improve flowability during the production of shaped articles.
Known such additives or releasing agents are such natural waxes as paraffin waxes, montan waxes and derivatives of these waxes, and such synthetic waxes as higher fatty acid ester waxes and polyolefin waxes containing ethylene or propylene as essential ingredient (for example, polyethylene waxes, polypropylene waxes). These waxes are inexpensive and provide good shaping processability and good surface conditions, finding wide use. However, the natural waxes, for example montan waxes, have a problem in stable supply because the extractability thereof from minerals is unstable.
Releasing agents based on fluorine, silicone or copolymer thereof allow for excellent mold-releasing properties because of their low critical surface tension and can maintain the mold-releasing properties for long term (Patent Literatures 1 and 2). Although these additives provide good shaping processability or mold-releasing properties in the shaping of synthetic resins, they have low compatibility with the resins and consequently separate and diffuse after the shaping to bleed out on the surface of shaped articles. The bleed out deteriorates the appearance and can adversely affect secondary processability (e.g., printing, coating). Further, many of the releasing agents based on fluorine, silicone or copolymer thereof are generally expensive compared to the wax-based releasing agents. These existing releasing agents have defects as described above, and there have been no resin compositions which contain a satisfactory releasing agent in terms of both shaping processability and secondary processability on the surface of shaped articles.